21233218 has 8 divisors (see below), whose sum is σ = 32286348. Its totient is φ = 10471104.

The previous prime is 21233213. The next prime is 21233239. The reversal of 21233218 is 81233212.

It can be written as a sum of positive squares in 2 ways, for example, as 20675209 + 558009 = 4547^2 + 747^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21233213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72571 + ... + 72862.

It is a self-describing number.

Almost surely, 2^21233218 is an apocalyptic number.

21233218 is a deficient number, since it is larger than the sum of its proper divisors (11053130).

21233218 is a wasteful number, since it uses less digits than its factorization.

21233218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145508.

The product of its digits is 576, while the sum is 22.

The square root of 21233218 is about 4607.9516056487. The cubic root of 21233218 is about 276.9099786975.

The spelling of 21233218 in words is "twenty-one million, two hundred thirty-three thousand, two hundred eighteen".